Manufacture of foils



Filed April 28, 1932 Patented Jan. 14, 1936 UNITED STATES PATENT CFFICE MANUFACTURE F FOILS Max Hagedorn, Dessau in Anhalt, Germany, as-

signor to Agfa Ansco Corporation, Binghamton, N. Y., a corporation of New York Application April 28, 1932, Serial No. 608,111 In Germany April 29, 1931 4 Claims. (Cl. 91-68) My present invention relates to foils and vmore erties of sheets saponied on both faces are comparticularly to sheets made of organic cellulose pared with those of sheets which have not been esters. thus saponified. The saponiflcation is effected One of its objects is to provide foils having with a methanolic sodium hydroxide solution of 5 improved physical properties. Further objects 10 per cent strength to which 10 percent of Water 5 will be seen from the detailed specification folhas been added. Aqueous solutions of sodium lowing hereafter. Films and sheets are made of hydroxide can likewise be used. In this case, organic cellulose esters, for instance of cellulose however, the saponication takes more time. acetate, cellulose propionate,` cellulose butyrate, Inorganic and organic acids in an aqueous solucellulose nitrate acetate, cellulose acetate butytion or in organic solvents may likewise be used. 10 rate, with or Without addition of softening agents, The saponication may be effected byv dipping filling agents, etc. Furthermore it is known to the materials to be treated in the liquid for the superilcially saponify lms, made of organic cellutime wanted or by passing them through the lose esters, on one of their faces. liquid on a suillcient length or in other known According to this invention improved mechani# manner. 15 cal properties can be imparted to lms and foils The experiments have been performed with made of cellulose esters by saponifying them lms of 13S/t to 1507i thickness. The cross secsuperflcially on both faces in suchamanner that tion of a lm after a treatment of about 10 the internal portion of the foil is not attacked minutes showed that the saponication with a 0 by the saponifying agent. The lm thus obtained lye of the aforesaid strength had penetrated from 20 comprises an internal portion consisting of unboth sides to about V; of the thickness of the saponifled cellulose ester and two external porlm, while the remaining oi the lm had not tions of cellulose which has been regenerated more been saponifled.

l A' irimct te El u y epenonga on Duration ot saponiilcation lilig Ign im duhxi in water kilos per cc.

so Films made of hydrolyzed cellulose acdate (containing 54% of bound acetic acid) having on addition of 3G a softening oyent 82 25 47 l l 0 85 103 3 28 84 31 113 119 3 34 p0 92 as 122 157 3 51 36 Saponlfied for 16 minutes 96 36 175 200 3 80 Saponiiled for 20 minutes 96 37 245 270 4 29 Film made of hydrolyzed cellulose acetate (containing 54% of bound acetic acid) without addition of a softening ayant 40 Films made of hydrolyzed cellulose acetate (containing 64% of bound acetic acid) 45 Non-saponiiied 83 2l. 8 62 Saponitled on one side (for 25 min.).... 82. 7 22. 7 54 or less completely. The internal portion inter- For the sake of better comparison the un- 50v miXeS With the external Portions at point gf con treated material has also been extracted with tact 5 that no Wen dened borders are orme the liquid used in the saponiflcation process for n f the film is thus as and a' perfect coheslo o dissolving the saponifying agent, in the present sured. In the following tables the mechanical propcase methanol. lIhe characteristics of this ma- 65 terial are given in the second horizontal column of the first and the second table.

As seen from the above table the new sheets possess improved mechanical properties. However, the elongation when wetted with Water is likewise increased and that may be disadvantageous for certain uses. By the following treatment the elongation in water may be diminished while the improvements of the mechanical properties obtained by the saponiflcation may at the same time be preserved. It consists in esterifying superficially the outer layers consisting of regenerated cellulose only to a small depth, or providing them with a thin coating of a colloid which is less sensitive to water than is regenerated cellulose; all of the known esters, mixed esters, ether-esters and ethers of cellulose, as well as natural and artificial resins are suitable for this purpose.

The following examples illustrate the invention:

Example 1.-A film of hydrolyzed cellulose acetate the two faces of which are saponii-led superficially is provided with a coating of 5 to 8a thickness consisting of a solution of Grams Nitrocellulose L 100 Polyvinyl acetate resin 50 v Phthalic acid dimethylester 30 Triphenylphosphate 20 Acetone 1700 Ethanol 300 Example 2.-A illm of hydrolyzed cellulose acetate the two faces of which have been saponifled superficially are treated at a temperature of C. for 15 minutes with a mixture consisting of:

Parts Acetic anhydride 10 Butyric anhydride 10 `Glacial acetic acid; 40

The esteriilcation hereby obtained penetrates by about 10a into the film.

The sheets according to this invention are suitable for all purposes of application, for which there was hitherto made use of the unsaponified cellulose ester foils. More particularly they are suitable for use as supports for photographic dvestuifs, gliding agents, softening agents, filling agents etc. by bathing the material in suitable solutions or suspensions. In the case of sheets the surface of which has been subjected to a treatment preventing a too great elongation in the wet state, and if desired in the case of sheets having a saponifled surface, the surface of the foils may be provided with a special preparation layer ensuring the adhesion of the photographic emulsion layer. l0

In the accompanying drawing:

Fig. 1 is a diagrammatic illustration,

Fig. 2 is a diagrammatic illustration of a specific embodiment of the invention.

In the accompanying drawing there are dia- 15 grammatically illustrated the two kinds of sheets, the drawing being in itself explanatory. The lines of separation seen in the drawing dividing the saponiiied layers and the middle part of the sheet do not exist in reality, the layers inter- 20 mingling as already explained. These lines have only been drawn to give a clearer idea of the invention.

What I claim is:

1. A laminated sheet comprising an internal 25 stratum comprising an organic cellulose ester and adjacent to said internal portion and blended therewith at point of contact on both faces external strata of regenerated cellulose bearing on their outer surfaces and firmly adhering thereto a layer of a colloid less sensitive to water than cellulose hydrate.

2. A laminated sheet comprising an internal stratum comprising an organic cellulose ester, and

adjacent to said internal stratum and blended 35 strata of regenerated cellulose and adjacent said 45' middle portions and blended therewith at point of contact external strata of cellulose acetate.

4. A laminated sheet comprising an internal stratum comprising an organic cellulose ester and adjacent to said internal stratum and blended 50 therewith at point of contact on both faces strata of regenerated cellulose bearing on their outer surface and firmly adhering thereto layers consisting of nitrocellulose, polyvinyl acetate resin, phthalic acid dimethylester, and triphenyl phosphate.

MAX HAGEDORN. 

